Age-related changes in the mouse outer retina

Purpose. To define the physiological and structural changes that may accomp any aging in the normal mouse retina. Methods, C57BL/6 mice were maintained under cyclic light for either 2, 6, or 12 months. After rod- and cone-medi ated corneal electroretinograms (ERG's) were recorded from anesthetized ani mals, the retinal structure was quantitatively examined. Photoreceptor cell density was measured within 100-mum regions of the central superior and in ferior retina. Cone photoreceptor subtypes were identified by immunocytoche mistry. Results. The amplitudes of rod- and cone-mediated ERG's were reduce d in older mice, although the overall ERG wave-form did not change apprecia bly and implicit times were not changed in an age-dependent fashion. In com parison, there was no significant age-related decline in rod or cone photor eceptor density. Conclusions. The amplitude of the mouse ERG declines with age. This change does not appear to reflect a change in the structural inte grity of the photoreceptor cells. In functional studies of murine models of late-onset retinal disorders, it will be important to take these changes i nto consideration.